Spatial indexing for WKT-based geometries works correctly for POLYGON shapes, but fails for MULTIPOLYGON geometries #21613

public class DocumentWithSpatial
  {
      public string Id { get; set; } = null!;

      public string SpatialWkt { get; set; } = null!;
  }

  public class Areas_ByGeometry : AbstractIndexCreationTask<DocumentWithSpatial>
  {
      public class Result
      {
          public string Id { get; set; } = null!;
          public object Geometry { get; set; } = null!;
      }

      public Areas_ByGeometry()
      {
          // Corax doesn't support WKT-based spatial indexing yet.
          SearchEngineType = Raven.Client.Documents.Indexes.SearchEngineType.Lucene;
          Map = documentsWithSpatial =>
              from documentWithSpatial in documentsWithSpatial
              select new
              {
                  documentWithSpatial.Id,
                  Geometry = CreateSpatialField(documentWithSpatial.SpatialWkt),
              };
      }
  }

  [Fact]
  public async Task SortByDistance_FailsForMultiPolygonIndexing()
  {
      var furthest_field_id = "furthest-field-id";
      var furthest_field_wkt =
          "POLYGON ((17.384491 45.576682, 17.391958 45.577643, 17.387323 45.580166, 17.384491 45.576682))";

      var closer_field_id = "closer-field-id";
      var closer_field_wkt =
          "MULTIPOLYGON (((17.384491 45.576682, 17.391958 45.577643, 17.387323 45.580166, 17.384491 45.576682)),((17.401743 45.580947, 17.408781 45.579565, 17.414446 45.584731, 17.409124 45.587014, 17.401571 45.585693, 17.401743 45.580947)))";

      var closest_field_id = "closest-field-id";
      var closest_field_wkt =
          "POLYGON ((17.420797 45.582028, 17.422857 45.579385, 17.428007 45.579325, 17.429895 45.582509, 17.428522 45.584731, 17.423286 45.584551, 17.420797 45.582028))";

      var longitude = 17.418308;
      var latitude = 45.582269;

      var documentsWithSpatial = new List<DocumentWithSpatial>
      {
          new() { Id = closer_field_id, SpatialWkt = closer_field_wkt },
          new() { Id = furthest_field_id, SpatialWkt = furthest_field_wkt },
          new() { Id = closest_field_id, SpatialWkt = closest_field_wkt },
      };

      using var store = StoreItemsToTestDb(documentsWithSpatial);
      await store.ExecuteIndexAsync(new Areas_ByGeometry());
      WaitForIndexing(store);

      using var session = store.OpenAsyncSession();


      //This will throw Spatial4n.Exceptions.ParseException for MULTIPOLYGON
      var result = await session
          .Query<Areas_ByGeometry.Result, Areas_ByGeometry>()
          .OrderByDistance(x => x.Geometry, latitude, longitude)
          .ToArrayAsync();

      Assert.NotNull(result);
      Assert.Equal(3, result.Length);
      Assert.Equal(closest_field_id, result[0].Id);
      Assert.Equal(closer_field_id, result[1].Id);
      Assert.Equal(furthest_field_id, result[2].Id);
  }